Terry — The Naaal Skeleton of Amhlystoma punctatum. 12S 



'02. Wiedersheim, R., Vergleichenden Anatomie der Wir- 



belthiere, 5 Auflage. 1902. 

 '91. Wilder, H. H., A contribution to tlie anatomy of Siren 



lacertina. Zool. Jahrb. IV. 1891. 

 '92. Wilder, H. H., Die Nasengegend von Menopoma alleg- 



haniense und Amphiuma tridactylum . Zool. Jahrb. V. 



1892. 

 '03. Wilder, H. H., The skeletal system of Necturus macula- 



tu8. Mem. Bost. Soc. Nat. Hist. V. 1903. 

 '98. Winslow, G. M., The chondrocranium in the Ichthyop- 



sida. Tufts College Studies, No. 5, 1898. 



DESCRIPTION OF FIGURES. 



The drawings of the wax-modela have been made by Dr, R. W. Mills of 

 the Washington University Medical Department. The tracings of the 

 transections were made with the camera lucida. 



Fig. 1. Model of Stage I, showing the anterior part of the brain, left eje- 

 ball and nasal sac, the trabecular horns and ethmoidal columns. About ^ . 



Fig. 2. Model of Stage II, showing the right half of the anterior end of 

 the brain, the left eye-ball and nasal sac; the changes in the ethmoidal col- 

 umn and other parts of the ethmoidal skeleton appear. About ^. 



Fig. 3. Model of Stage III. The ethmoidal skeleton and the left nasal 

 sac are shown. The latter, as in Fig. 2, is sectioned caudad of the external 

 naris. The olfactory and ethmoidal windows are present. About ^.j 



Fig. 4. Model of Stage IV. Left nasal sac and left half of the ethmoidal 

 skeleton. The nasolacrimal duct and the nerves of this region are shown. 

 About V- 



Fig. 5. Transection passing through the anlage of the ethmoidal column, 

 showing also the column of cells between it and the trabecula. Ambly- 

 etoma 12 mm. 



Fig. 6, Transection at the level of the base of the antorbital process and 

 cephalic end of the trabecular crest. Stage II. XV* 



Fig. 7. Transection at the level of the middle of the ethmoidal column 

 and olfactory bulb. Stage II. X V- 



Fig. 8. Transection passing through Jacobson's organ and gland at the 

 level of the caudal edge of the trabecular horn. Stage III. X V- 



